package com.demo.common;

import java.net.InetAddress;
import java.util.ArrayList;
import java.util.List;

/**
 * 唯一主键生成办法。<br>
 * 从Hibernate中提取出来。
 */
public class UUIDGenerator {

	/**
	 * 分隔符
	 */
	private final static String sep = "";
	
	private static final int IP;

	public static int IptoInt(byte[] bytes) {
		int result = 0;
		for (int i = 0; i < 4; i++) {
			result = (result << 8) - Byte.MIN_VALUE + (int) bytes[i];
		}
		return result;
	}

	static {
		int ipadd;
		try {
			ipadd = IptoInt(InetAddress.getLocalHost().getAddress());
		} catch (Exception e) {
			ipadd = 0;
		}
		IP = ipadd;
	}
	private static short counter = (short) 0;
	private static final int JVM = (int) (System.currentTimeMillis() >>> 8);

	public UUIDGenerator() {
	}

	/**
	 * Unique across JVMs on this machine (unless they load this class in the
	 * same quater second - very unlikely)
	 */
	protected int getJVM() {
		return JVM;
	}

	/**
	 * Unique in a millisecond for this JVM instance (unless there are >
	 * Short.MAX_VALUE instances created in a millisecond)
	 */
	protected short getCount() {
		synchronized (UUIDGenerator.class) {
			if (counter < 0)
				counter = 0;
			return counter++;
		}
	}

	/**
	 * Unique in a local network
	 */
	protected int getIP() {
		return IP;
	}

	/**
	 * Unique down to millisecond
	 */
	protected short getHiTime() {
		return (short) (System.currentTimeMillis() >>> 32);
	}

	protected int getLoTime() {
		return (int) System.currentTimeMillis();
	}

	protected String format(int intval) {
		String formatted = Integer.toHexString(intval);
		StringBuffer buf = new StringBuffer("00000000");
		buf.replace(8 - formatted.length(), 8, formatted);
		return buf.toString();
	}

	protected String format(short shortval) {
		String formatted = Integer.toHexString(shortval);
		StringBuffer buf = new StringBuffer("0000");
		buf.replace(4 - formatted.length(), 4, formatted);
		return buf.toString();
	}

	public String generate() {
		return new StringBuffer(36).append(format(getIP())).append(sep)
				.append(format(getJVM())).append(sep)
				.append(format(getHiTime())).append(sep)
				.append(format(getLoTime())).append(sep)
				.append(format(getCount())).toString();
	}
	
	//生成16位uuid的long型
	public Long generateLong() {
		return Long.parseLong(new StringBuffer(17).append(format(getHiTime())).append(sep)
				.append(format(getLoTime())).append(sep)
				.append(format(getCount())).toString(), 16);
	}
	
	public long generateShort() {
		return Long.parseLong(new StringBuffer(17).append(format(getHiTime())).append(sep)
				.append(format(getLoTime())).append(sep)
				.append(format(getCount())).toString(), 16);
	}
	
	public static void main(String[] args) throws InterruptedException {
		
		Long time = System.currentTimeMillis();
		
		UUIDGenerator uuid = new UUIDGenerator();
		List<Long> pop = new ArrayList<Long>();
		while(true) {
			for (int i = 0 ; i < 100; i ++) {
				long uuids = uuid.generateLong();
				//Thread.sleep(998);
				if (pop.contains(uuids)) {
					System.err.println("error in the generate id:" + uuids);
				}
				pop.add(uuids);
				System.out.println(uuids<<8);
				System.out.println(Long.toHexString(uuids>>>1));
			}
			System.out.println(System.currentTimeMillis() - time);
			Thread.sleep(15000);
			//long uuids = uuid.generateLong();
		}
	}

}
